Galaxy Formation

I review the current status of theoretical studies of galaxy formation. I outline the importance of the physics of baryonic component in galaxy formation by showing results obtained by using two major tools, semi-analytical approaches and cosmological simulations. In particular, I emphasis on roles of feedback in galaxy formation and discuss whether apparent conflictions between the standard theory of structure formation, the cold dark matter model, and observations can be solved by the feedback. I also discuss future prospects in numerical simulations of galaxy formation.